1. Field
Aspects of the present invention generally relate to ophthalmologic apparatuses, methods for controlling ophthalmologic apparatuses, and programs.
2. Description of the Related Art
Among existing ophthalmologic apparatuses, in a fundus camera, for example, a working distance between an eye to be examined and the ophthalmologic apparatus in an optical axis direction is adjusted to an appropriate distance prior to capturing an image of a fundus of the eye to be examined. In one of the known methods for adjusting the working distance, a cornea reflection image of a target that has been projected on a cornea of an eye to be examined is observed on a monitor, and the target is manually brought into focus. In addition, known is a configuration in which an ophthalmologic apparatus automatically determines whether the working distance is appropriate based on information on a luminance value distribution of a cornea reflection image of a target that has been projected on a cornea of an eye to be examined and the ophthalmologic apparatus automatically captures an image upon determining that the working distance is appropriate.
Japanese Patent Laid-Open No. 06-046999 discloses a fundus camera in which two types of targets, namely a finite distance target of a finite distance and an infinite distance target, are projected on an eye to be examined and the working distance is calculated from the positional relationship between the finite distance target and the infinite distance target so as to determine whether the working distance is appropriate.
In addition, Japanese Patent Laid-Open No. 07-031590 discloses a fundus camera in which optical members are disposed such that a target is offset when the working distance is not appropriate and the target matches when the working distance becomes appropriate and whether the working distance is appropriate is determined by determining an offset of the target.
It is difficult, however, for an examiner to determine whether the working distance between the eye to be examined and the ophthalmologic apparatus is greater or less than an appropriate working distance at a point at which the examiner is trying to adjust the working distance while observing a reflection image of a target on a monitor. Thus, the examiner simply determines that the working distance is not appropriate in a state in which the target is out of focus while observing the reflection image of the target projected on the monitor and moves the apparatus body back and forth in the optical axis direction. Based on the result of such an operation, the examiner determines whether the working distance between the eye to be examined and the apparatus body is greater or less than the appropriate working distance and then moves the apparatus body so as to bring the working distance to an appropriate working distance. The examiner can thus finish adjusting the working distance by repeating such operations. Accordingly, it is difficult to promptly capture an image of the fundus of the eye to be examined.